Salicylic Acid

Salicylic acid is an organic acid that has a colorless crystalline structure and is poorly soluble in water. Salicylic acid is a beta-hydroxy acid, which is a larger molecule than alpha-hydroxy acids (AHAs) and is widely used in topical formulations as a comedolytic and keratolytic agent.1,2,3,4

Beta-hydroxy acids (BHAs) are derived from plant hormones and are lipid soluble. Salicylic acid, or 2-hydroxybenzoic acid, is extracted from the bark of the willow tree, and systemic formulations provide pain relief and anti-inflammatory effects. Salicylic acid applied topically penetrates pores which contain sebum, thereby softening and removing the epithelium. Its larger molecular size limits penetration through the dermis to general circulation. Salicylic acid has been combined effectively with other ingredients for various topical applications.1,2,3

Salicylic acid has been derived historically from plants, specifically the bark of the white willow tree and the meadowsweet herb. Ingestion of extracts has been reported to be effective in relieving pain, fever, and inflammation, as well as causing gastric upset.4,5 In 2000, the FDA evaluated the safety of BHAs and alpha-hydroxy acids (AHAs) as exfoliants and found that salicylic acid in cosmetics is "safe for use when formulated to avoid irritation and when formulated to avoid increased sun sensitivity."1

Salicylic acid has been shown to be effective in dermatologic and cosmetic applications for its rapid effect as a keratolytic agent. Products containing salicylic acid include facial cleansers and antidandruff shampoos. Salicylic acid has been added in trace amounts as a food preservative and in mild antiseptics, such as mouthwashes and toothpastes. Salicylic compounds have also been synthesized for analgesics (acetylsalicylic acid or aspirin) and antipyretics (phenyl salicylate or salol). The methyl derivative of salicylic acid, methyl salicylate, is the chief constituent of oil of wintergreen.3,4

Salicylic acid is available in varying concentrations and grades, depending on intended use. Trace amounts are used as a food preservative and in over-the-counter antiseptics and antipyretics. Pharmaceutical-grade salicylic acid undergoes a complex series of filtration and purification processes. For skin applications, salicylic acid is used in concentrations ranging from 2% to 6% for hyperkeratotic and scaling conditions, with clinical use above 6% concentration in peels, suspensions, and ointments. The pH of the product can be buffered.4,5,6,7,8,9,10

The effects of salicylic acid as a keratolytic and mild antiseptic result in rapid desquamation of keratin. Its lipid solubility is central to its ability to penetrate pores and aid in the absorption of other agents.

The peeling effect of salicylic acid has been demonstrated using low and moderate concentrations with a low pH to promote keratolysis, the separation of the epidermal layer from the dermis through accelerated cell loss. Salicylic acid inhibits COX-1 synthesis and affects the prostaglandin pathway by weakening of the intercellular corneocyte bonds that disrupts the adhesion of corneocytes in the lower stratum corneum, causing a separation of the bulky upper layer from the newly formed lower layer.5,7,8,9,10

The rapid onset and limited absorption of salicylic acid has been shown to be an effective agent for comedolysis and keratolysis. Varying concentrations of salicylic acid provide benefits in local and general topical use, and for targeted and repetitive applications.3,5,6 Products containing salicylic acid optimize its effect to support penetration of other agents and devices.11,12 In 2000, the Cosmetic Ingredient Review (CIR) Expert Panel for the FDA provided guidelines for the safe use of products containing beta-hydroxy acids by consumers.1,2,3 Clinical studies demonstrate that the systemic absorption of topical salicylic acid when applied by healthcare professionals is minimal to none, and can be used with caution in children and pregnant women.2,3,4,5

The comedolytic and keratolytic benefits of topical salicylic acid are effective in low and moderate doses for the treatment of acne infections of varying severity, including papules, pustules, nodules, cysts. Salicylic acid has also been demonstrated to be effective in the prevention of acne on skin prone to this type of infection.6,8,12,13 Combination therapy with salicylic acid is preferred in recalcitrant cases.14

The keratolytic effect of topical salicylic acid results in the desquamation of the epidermis, promoting dermal matrix regeneration. Combination treatment can optimize the texture and tone of treated skin.15,16

The lipid solubility of salicylic acid is effective in penetrating sebaceous pores for subsequent dissolution of acne bacteria. The comedolytic effect of salicylic acid results in the breakdown of clogged pores to express fluid and extrude ingrown hairs, restoring pore structure to its natural state. Care should be taken in areas that present abrasions or cuts to avoid possible systemic absorption.16,17,18

Seborrheic dermatitis causes flaking of the skin, usually recognized on the scalp as dandruff and affecting other parts of the body such as the face and chest, as well as the creases of the arms and legs. The keratolytic properties of salicylic acid facilitate the replaning of these areas, reducing skin buildup and the oily appearance that can result from the condition.17,18,19 Etiology of the condition can be hormonal or fungal-the mild antiseptic properties of salicylic acid can provide some amelioration. Salicylic acid formulations in shampoos and cleansers for common, specific, or adjunctive treatments can be used as monotherapy or in combination with prescription steroids.

The fine scales that result from xeroderma and ichythosis have been successfully treated with 6% salicylic acid gel, in conjunction with routine application of hydrating agents and medications.20,21 Chronic treatment for these conditions and diseases should be monitored by a healthcare professional, as eruptions and epithelial thickening are associated with the conditions.

Warts are abnormal noncancerous growths caused by the human papillomavirus (HPV). Outbreaks from viral infections can be treated; eruptions can also regress over time. Salicylic acid is a primary ingredient in effective over-the-counter remedies for wart removal. In a clinical setting, higher concentrations of salicylic acid are considered a nonsurgical alternative to laser surgery or cryosurgery.25

KAVI provides recommended instructions for all products for optimal results. Healthcare professionals should provide specific patient instructions based on the therapy (single or combination) and desired results. Instructions for use may be found at the following locations:

KAVI Salicylic Acid treatment provides healthcare professionals with flexibility in establishing the treatment plan. KAVI Salicylic Acid peels may be repeated weekly until the desired results are achieved. After an initial six to eight weekly applications, diminished results may be observed, indicating a resting phase. Following a one-month hiatus, another six- to eight-week treatment cycle may be repeated.

All products containing salicylic acid should be applied as directed. Improper use may result in acute skin irritation and inflammation. Patients using products containing salicylic acid are cautioned to use adequate sun block protection on exfoliated areas that may be exposed to sunlight. KAVI Salicylic Acid products with concentrations above 8% are contraindicated for hypersensitive skin and should be administered by trained professionals.

When salicylic acid is included as part of a treatment plan, healthcare professionals can select the specific product to meet the needs of their treatment plan. Salicylic acid products provide healthcare professionals the added flexibility of customizing post-treatment plans to include lifestyle and long-term goals. Factors to consider are outlined in the table below.

Physician Considerations

• What is the length of treatment?

• What is the product's salicylic acid concentration?

• What is the product's pH?

• How do the other active ingredients in the product support my patient's treatment?

• Are there any considerations for combination therapy or adjunctive use?

• Is the product easy for my patient to use?

KAVI Products have been developed to provide professionals with a line of high-quality products that can be configured for your treatment needs.